Incontinence refers to the involuntary excretion of urine or bowel contents by a person. This condition can happen when a person is in hospital, extended care facility, or home care environment. For some people, it is a short term condition, for example, right after medical operation in a post-anesthesia state. For some people, it is a medium term condition which may last for a few months, for example due to injuries. For some other people, it is a long term condition where the voluntary control of urinary tract or bowel is lost permanently. The incontinence condition will be particularly problematic for this last group of people if they are also unable to move because of paralysis, illness or old age.
Incontinence is a major contributing or aggravating factor for bed sores. Bed sores, or pressure ulcers, are injuries to skin and underlying tissue resulting from prolonged pressure on the skin. Prolonged pressure slows down blood flow to the skin and top layer of subcutaneous fat and muscle, and skin lesion will easily occur. When that happens, infection will arise if bacteria are allowed to go near. As a person lies on bed with the body underneath in a wet condition due to urine and/or bowel material (which contains a lot of bacteria), the skin of the person will become much more vulnerable to infection and therefore develop lesions much faster than if it is dry. It has been reported that bed sores can happen within one and a-half hour to two hours of staying on bed immobile. Once bed sores develop, it typically may take at least five additional days of hospital stay to treat it.
If the incontinent person lies on bed, a large rectangular medical pad is usually applied between the person and a mattress on which the person lies. A medical pad has two critical layers: a Super Absorbent Polymer (SAP) based water absorption layer, and a waterproof layer underneath the SAP layer. Using a medical pad, the moisture of any involuntary excretion can be absorbed with the primary purpose of keeping the person as dry as possible, and the secondary purpose of keeping the mattress clean and hygienic. If the mattress is messed up and cannot be effectively cleaned, it has to be cleaned or even replaced. Cleaning or replacing the mattresses is very expensive.
The existing medical pad, however, is not without shortcomings. For example, the existing medical pad cannot keep the person completely dry because there are crevices and parts of the body which are not in touch with the medical pad. Furthermore, the medical pad has its own maximum moisture capturing capacity, beyond which the person will still be wet. Since the medical pad is right underneath the patient, its wetness extent is not visible and the patient has to report the wetness to the nurse if the patient wants immediate relief or replacement of the medical pad. This is not always easy, especially for patients with reduced mobility or consciousness.
Because of this, a nurse still has to check the medical pad regularly to see if it is wet, and if wet, replaces it. To do the checking, the nurse needs to roll over the person and touch the medical pad to feel it and see if it is wet. The person, if sleeping, will often be woken up. In other cases, the person, with certain injuries to the body or the spine, may not fare too well with too many of these roll over actions. In fact, the roll over action itself, with the accompanying coldness felt by the patient as the back of the body is side way rolled away from the mattress, may actually become stimulation to the patient and cause the patient to become incontinent soon after the roll over event occurs.
Moreover, the nurse can only check the patient once in a while, with the time period longer or shorter depending on the availability of nurse resources in the hospital or extended care or home care facility. Therefore there will be a time lapse between the involuntary excretion and the time where the nurse will discover and replace the medical pad. Prolonged exposure to this wetness condition will aggravate or induce bed sores, technically known as pressure ulcers. Bed sore is very difficult to treat for bed-ridden persons, and causes major discomfort. In most cases, persons developing bed sores in hospital will cause an increase in total number of days of hospital stay—the extra days needed to medically treat this bed sore condition.
From 2015 onward, with the new Affordable Care Act in the US, if bed sores are acquired during the hospital stay, any extended hospital stay to treat bed sore is no longer covered by insurance. The hospital has to bear the cost of the extended stay.
General hospital practice to prevent bed sore is for the nurse to roll the patient over every two hours—this is assuming the patient is dry. If during this two-hour interval the patient becomes wet due to incontinence, then the aggravating effect of this wetness will make this two-hour “roll the patient” period not short enough. In fact, heavy incontinence can indeed happen in one or two hours, depending on the health situation and overall condition of the patient.
To overcome this, a better way is to have a medical pad that can sense this wetness and notify the nurse in a timely manner, so that the nurse can come to replace the pad. This will be a most useful device for incontinent persons, whether short term, medium term or long term.
Wetness detection or moisture monitoring has been around for many years. The earliest design consists of two wires 12, 14 or two printed conductive ink traces, as shown in FIGS. 1 and 2. Terminals of the two wires 12, 14 are connected to a resistance measurement device 16. When the area across the twin wires 12, 14 or traces is dry, as shown in FIG. 1, the electric circuit is an open circuit with a very high electrical resistance. When any area across the twin wires 12, 14 or traces is wet, and hence conductive, as shown in FIG. 2, the electric circuit is closed and the resistance becomes a lower finite value. A simple threshold will separate the open circuit and the closed circuit, and thus differentiates between dryness and wetness. This is the most basic design of wetness detection.
When one varies the width between the two lines 12, 14, one can control the sensitivity of the wetness detection. The wider the separation, the larger amount of liquid is required to short the circuit. This method is used for setting the sensitivity of the system to that desired by the user. Comparing the arrangement shown in FIG. 3 and that shown in FIG. 4, it can be seen that more liquid is required for electrically connecting the wires 12, 14 in FIG. 4 than for connecting wires 12, 14 in FIG. 3. In the case of medical pad, the nurse would certainly want to limit the warning or alert to happen only when the incontinence amount reaches a certain level. When there is only a very small amount of excretion, usually the medical pad can handle that. Only when the amount of excretion becomes so large that the medical pad can no longer effectively handle the situation, then the nurse has to come and replace the pad and also dry up the patient.
Using a twin-wire design to cover up a large rectangular area is possible, where one meanders a twin-wire 18 in a generally “Z” manner throughout the rectangular area, as shown in FIG. 5. This design has one flaw: the sensitivity of the area between the twin-wire 18 and the sensitivity of the area between two lengths of the meandering twin wire are different.
Other than the twin-wire design, a comb design, as shown in FIG. 6, is also very popular and has been around for many years. In this design, two terminals 20, 22 fan out to become each side of an interlocking pair of combs. In this design, the flaw of the twin wire design is overcome, where the sensitivity is the same throughout. This interlocking comb design, however, also has its own flaw. The ink printed trace has its own resistivity per length. As the trace travels down the comb farther and farther away from the incoming terminal 20, 22, the total resistance becomes larger and larger. This creates a problem in setting the threshold for wetness measurement.
It is thus an object of the present invention to provide a diaper, a wetness reporting system, a method of reporting wetness of a subject and a method of calibrating a wetness reporting pad of a diaper in which the aforesaid shortcomings are mitigated or at least to provide a useful alternative to the trade and public.